R_IsRCmp() 
 Determines if a file has been compressed by R_CmpFile()
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 Syntax
        nRetCode = R_IsRCmp ( cInFile [, cPassWord ] )

 Arguments
        cInFile         File specification of the file to be examined
                        Format  : [drive:][\path\]filename[.ext]
                        Example : C:\INVOICE\INVOICE.DBF

        cPassWord       If the file is compressed using a password, the
                        same password should be passed to this function.
                        Note : The password is case-sensitive !

 Returns
        nRetCode        0 = CP_OKAY             File IS compressed using
                                                R_CmpFile()
                        1 = CP_INVALID_PARM     Invalid parameter(s) passed
                        2 = CP_OPEN_INPUT       Error opening input file
                        3 = CP_NOT_RCMPLIB      File is NOT compressed
                                                using R_CmpFile() -or-
                                                Incorrect password
                        4 = CP_WRONG_VERSION    File compressed with an
                                                earlier RCmpLib version
                        6 = CP_READ_INPUT       Error reading input file

                        See also the item ErrorCodes in this guide.

 Description
        Determines if a file has been compressed using the R_CmpFile()
        function.

 Example
        *-- Check if the file TEST.RCP is compressed using R_CmpFile()

        nRetCode := R_IsRCmp ( 'TEST.RCP' )

        IF nRetCode = 0
           ?'File is a valid RCmpLib archive .... !'
        ENDIF

 .